


DEPARTMENT OF COMMERCE 



Technologic Papers 



OF THE 



Bureau of Standards 

S. W. STRATTON, Director 



No. 215 

[Part of Vol.16] 

DURABILITY OF SOLE LEATHER FILLED 

WITH SULPHITE CELLULOSE 

EXTRACT 



ROY C. BOWKER, Associate Physicist 
"i 

Bureau of Standards 



JUNE 10, 1922 




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DURABILITY OF SOLE LEATHER FILLED WITH 
SULPHITE CELLULOSE EXTRACT 

By Roy C. Bowker 



ABSTRACT 



Four lots of leather were prepared and tested to determine the comparative dura- 
bility of sole leather filled respectively with sulphite cellulose extract and witji the 
ordinary tanning materials such as chestnut wood extract and quebracho exjtract. 
Physical data obtained as to the actual service tests and chemical analyses of both the 
new and worn soles failed to disclose a quality difference between the two leathers. 



INTRODUCTION 

The importance of utilizing the wood substance contained in 
the waste sulphite liquor, which at one time was discharged from 
the pulp mills as useless waste, is evidenced by the large amount 
of research which has been conducted on the subject in every 
wood-pulp-producing country. 

One of the principal methods proposed for utilizing these waste 
liquors is the production of sulphite cellulose extract for use in 
making leather. This use of the material has been discussed with 
considerable interest, resulting in a remarkable diversity of opin- 
ion. It has been stated that the extract does not contain tanning 
properties, and hence is not a " true " tanning material as are such 
vegetable materials as oak bark, quebracho, and chestnut wood. 
It is generally considered that the material contains no tannin. 
However, experiments have shown that a hide treated with certain 
of the sulphite extracts will absorb as much as 25 per cent of sub- 
stances which will preserve the hide, which is the essential function 
of a tanning material. 

There are many different methods for treating the waste 
liquors to produce an extract for use in making leather, and hence 
there are correspondingly many different products. This 'may 
account in some measure for the varied results obtained from 
their use by investigators. Whether it is proposed to use the 
material either in tanning or filling, the waste liquor should be 
treated to remove such substances as iron and lime, which have a 
detrimental effect on the leather. 

103985°— 22 495 



496 Technologic Papers of the Bureau of Standards \voi.i6 

American tanners have not been successful in their attempts to 
tan hides with sulphite cellulose extract, and it is generally con- 
sidered as having no place in the tanyard. 

It has found, however, a wide application as a filling material 
in the manufacture of sole leather. After the hides have been 
thoroughly tanned in the yard they still lack the firmness and 
weight required. It is the general commercial practice to pro- 
duce these qualities by filling the leather with tanning materials 
by drumming, tempering, and dry dipping. 

Since the opinion has often been expressed that sole leather 
filled with this extract was inferior, and since no known data on 
the subject were in existence, this investigation was made to 
determine the comparative durability of sole leather filled with 
sulphite cellulose extract and sole leather filled with the ordinary 
vegetable tanning materials. 

DESCRIPTION OF LEATHER TESTED 

Several tanners were approached regarding the preparation of 
leather for the tests, and three different establishments were 
chosen in order that the leather used might be representative. 
The history of the various lots of leather tested follows : 

Lot No. i. — This tannery made two brands of leather commer- 
cially, one of which contained sulphite cellulose extract. Five 
hides were selected for the test. The tannage up to the wringer 
was a vat tannage of 60 per cent chestnut oak and 40 per cent 
chestnut. The leather was then filled with chestnut extract by 
drumming and finished in sulphited quebracho extract. Five 
alternate bends were then bleached, oiled, dried, and rolled. The 
five remaining bends were bleached, partially oiled, dried, dry 
dipped in sulphite cellulose extract, redried, oiled, and rolled. 

Lot No. 2. — Five hides were carried through the yard whole 
and then split after the third layer. Five bends were then ex- 
tracted in drums with the ordinary tanning materials, tempered, 
bleached, oiled, and rolled. The remaining five bends were 
drummed in 100 per cent sulphite cellulose extract, lightly 
bleached, oiled, dried, dry dipped in warm sulphite cellulose extract 
of 5 Twaddle, oiled, dried, and rolled. 

Lot No. 3. — In this tannery the hides were given 5 layers in 
the yard of 15 days each. No sulphite cellulose extract was used 
ordinarily in this tannery, but the company was interested in the 
proposed tests and prepared samples as desired. Four hides were 



Bowker] 



Sulphite Cellulose Extract 



497 



carried through the yard and were removed after the fourth layer. 
Four bends were then extracted in drums with ioo per cent sul- 
phite cellulose extract, then tempered 5 days in a 50 barkometer 
tempering liquor of the same extract, oiled, dried, dry dipped 
in 70 barkometer liquor made from sulphite cellulose extract, and 
finished as usual. The remaining four bends were extracted in 
drums with a mixture of chestnut wood extract and quebracho 
extract (50 per cent each), then tempered 5 days in a 50 bark- 
ometer tempering liquor made up of 50 per cent each of chestnut 
wood and quebracho extract, oiled, dried, dry dipped in 70 bark- 
ometer chestnut wood liquor, and finished as usual. 

Lot No. 4. — This leather came from the same tannery as did 
lot No. 3. Four hides were used and the bends were removed 
after the fifth and last layer instead of after the fourth layer, as 
in lot No. 3. The two groups of bends received the same treat- 
ment given those in lot No. 3, with the exception of dry dipping, 
which was omitted. 

WEAR TESTS 

After the leather was received at the laboratory full soles were 
cut and matched for test in a manner similar to that described in 
Technologic Paper No. 138, so that the soles of each pair were cut 
from similar locations on the same hide. One sole of each pair 
contained sulphite cellulose extract and one contained the ordinary 
vegetable tanning materials used in the tannery which furnished 
the leather. 

The leather was subjected to actual wearing test on laborers, 
laboratory workers, and office workers. The conditions of service 
were not uniform for all the different pairs of soles, some of which 
were worn on concrete floors, in machine shops, in boiler rooms, 
or in outside weather conditions. 

TABLE 1.— Results of Wear Tests 



Lot No. 


Pairs of 
soles 
tested 


Average iron per 
sole 


Days wear per sole 


Days wear per iron 




O" 


Sb 


O 


S 


O 


S 


1 


73 
90 
54 
63 


9.91 
9.60 
8.69 
8.44 


9.66 

9.54 
8.51 
8.48 


118.7 
94.4 
59.6 
63.7 


115.7 
90.5 
58. 1 
67.9 


11.97 
9.84 
6.86 
7.55 


11.98 


2 


9.49 


3 


6. 83 


4 


8.01 






Average 




9.16 


9.05 


84.1 


83. 1 


9.06 


9.08 









a O= Soles filled with ordinary vegetable tanning materials 

b S= Soles filled either entirely or partially with sulphite cellulose extract 



498 • Technologic Papers of the Bureau of Standards 

CHEMICAL ANALYSES 



[Vol. 16 



The following tables give the complete analyses for the different 
leathers both for the new and worn soles : 

TABLE 2. — Analyses of New and Worn Soles, Based on 12 Per Cent Moisture 

Content 

NEW SOLES 



Material 


Lot No. 1 


Lot No. 2 


Lot No. 3 


Lot No. 4 


O 


Sb 


O 


s 


O 


S 


O 


S 




25.19 
30.53 

3.09 
.21 
28.98 
93 

3.17 

1.54 

.23 

15.06 

10.12 

2.35 


31.69 
28.02 

3.06 
.29 
24.94 
87 

7.86 

1.85 

.05 

19.37 

12.27 

3.38 


26.81 
33.62 

4.49 
.17 
22.91 
66 

5.87 

2.04 

.53 

16.34 

10.47 

1.52 


28.96 
34.11 

4.38 
.25 
20.30 
58 

6.78 

2.22 

.95 

13.24 

15.75 

1.96 


31.53 
31.01 

4.51 

.23 

20.72 

64 

11.02 

1.76 

.53 

13.07 

18.49 

2.66 


29.01 
34.00 

4.61 
.29 
20.09 
57 
11.32 

1.77 

.48 

11.63 

17.40 

2.50 


24.30 
37.42 

3.38 
.19 
22.71 
58 

4.45 

1.26 

.14 

11.68 

12.62 

1.93 


25.25 


Hide substance 


35.60 




4.12 




.29 




22.74 




62 


Glucose 


2.48 


Total ash 


1.47 




.10 




15.95 


Snliihlp nnntans 


9.30 




2.36 







Worn Soles 





17.81 

35.62 
3.52 
2.46 

28.59 

80 
1.00 
3.97 
.30 
9.61 
8.20 
2.44 


19.87 

31.70 
3.90 
4.43 

28.10 

89 

2.42 
5.70 
.15 

10.83 
9.04 
2.63 


18.73 

34.37 
6.04 
4.66 

24.20 

71 

2.52 
5.82 
.59 
8.10 

10.63 
2.25 


18.67 

34.75 
5.44 
5.24 

23.90 

69 
2.21 
7.59 
.73 
8.24 

10.43 
1.35 


20.40 
34.75 
5.94 
3.88 
23.03 
66 

2.90 
5.10 
.58 
10.30 
10.10 
2.57 


19.57 

36.30 
5.51 
5.04 

21.58 

60 
2.68 
6.86 
.44 
9.20 

10.37 
2.15 


18.44 

35.40 
6.31 
6.49 

21.36 

60 
2.21 
7.80 
.25 
9.06 
9.38 
1.78 


17.16 




35.55 




5.35 




5.78 




24.16 




68 




1.93 


Total ash 


7.56 




.25 




9.81 




7.35 


Epsom salts • 


2.13 







tt O= Leather filled with ordinary vegetable tanning materials 

b S= Leather filled entirely or partially with sulphite cellulose extract 

The results of the chemical analyses, broadly interpreted, indi- 
cate that from the analytical standpoint the quality of the leather 
was not impaired by filling with sulphite cellulose extract. A 
greater increase in the degree of tannage after wear for the sul- 
phite-filled leathers than for the leathers .filled in the usual man- 
ner is shown for each lot. The analyses also indicate that the 
sulphite cellulose extract is as well fixed in the leather as are the 
vegetable tanning materials such as. chestnut and quebracho, 
and certainly more fixed than glucose, which was practically all 
withdrawn from the leather during wear, corrobrating previous 
data on this subject. 

Under ordinary service conditions it would also be expected 
that most of the Epsom salts would be withdrawn from the leather 
during wear. In this particular series of tests many of the indi- 



Bcrwker] 



Sulphite Cellulose Extract 



499 



viduals wearing test soles worked with such materials as lime, 
cement, and magnesite. It is therefore not surprising that the 
analyses of the worn soles show no appreciable loss in Epsom salts. 

In lot No. i, the glucose content of the leather filled with sul- 
phite cellulose extract is considerably more than the glucose 
present in the leather filled with the ordinary vegetable materials. 
This can be explained by the fact that the tanner of these leathers 
uses a greater amount of glucose in filling the former leather than 
is the custom in filling his regular tannage. 

The large difference in glucose content between lots 3 and 4, 
which were made by the same tanner, is caused by the fact that 
lot No. 3 was removed after the fourth layer instead of after the 
fifth layer, as for lot No. 4. Lot No. 3 was then in a slack tanned 
condition and would more readily absorb a greater amount of 
glucose than leather more thoroughly tanned, as was lot No. 4. 

TABLE 3.— Analyses of Sulphite Cellulose Extracts Used 



Material 



Used in 


Used in 


lot No. 1 


lot No. 2 


30.09 


26.56 


24.71 


25.12 


.07 


.00 


45.13 


48.33 


54.87 


51.68 


54.80 


51.68 



Used in 

lots No. 3 

and 4 



Materials absorbed by hide powder 

Nontannins 

Insolubles 

Moisture 

Total solids 

Soluble solids 



27.25 
24.30 
.12 
48.33 
51.67 
51.55 



Analysis of lot No. 1 was made from sample furnished by the 
tannery. The remaining analyses were furnished by the tanners 
who furnished the leather to which reference is made by the lot 
numbers. The tanners of lot Nos. 1, 3, and 4 referred to the sul- 
phite cellulose extract used, as "spruce extract." The tanners 
of lot No. 2 referred to the sulphite cellulose extract used as that 
manufactured by the Robeson Process Co., New York City. 

The tanners who furnished the leathers were C. C. Smoot & 
Sons, The American Oak Leather Co. , and the Ashland Leather Co. 

SUMMARY 

As a result of these tests the following observations can be made 
regarding the sulphite cellulose extracts used in this investigation 
as fillers for sole leather : 

1. Leather filled either partially or entirely with sulphite cel- 
lulose extract is as durable as leather filled with the ordinary tan- 
ning materials, such as chestnut and quebracho. 



018 455 014 3 



500 



Technologic Papers of the Bureau of Standards [Vol. 16 



2. As reflected by the chemical analyses, this extract is equally 
as firmly fixed in the leather as these vegetable tanning materials. 

3. The use of such a material instead of chestnut and quebracho 
would conserve these materials for use in the actual tanning proc- 
esses for which they are suitable and for which sulphite cellu- 
lose extract has not been successfully used. 

4. It is probable that this material could be used as a filler in 
place of the more soluble glucose, thereby producing a more 
waterproof leather. 

5. Leather filled with this material can be made which will 
have as light and uniform a color as leather filled with the ordi- 
nary materials. This was the case for lots No. 1 and 2. There 
was a slight difference in the color in lots No. 3 and 4, the leather 
filled with sulphite cellulose extract being a little darker. 

6. Using this material as a filler has no more effect on the aging 
of the leather than the ordinary materials, since samples of these 
leathers which have been in the laboratory for over two years 
are still in a satisfactory and pliable condition. 

Washington, April 8, 1922. 



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